A word of warning... this is a post about predation and the pictures reflect that.
River Otters moved into Rodeo lagoon in the Marin Headlands about 4 years ago and the resident birds were ill prepared.

They became instant celebrities and many people went to the lagoon to try and catch a glimpse of the group. They started out seven strong but have since become a quartet.

Like lions on the Serengeti, they carefully stalk their prey. In this instance they were after mallards on the shore. Their main technique seems to be:
1. Locate prey floating in the lagoon
2. Submerge and close the distance underwater
3. Grab the prey from below and asphyxiate with a bite to the neck or drowning
Cute huh?

A juvenile gull snatched from mid-lagoon.

A Heermann's Gull too slow to react gets caught and brought to a nearby dining spot.

After the hunter gets its fill the meal gets shared with the other otters waiting their turn. The number of feathers stuck in the vegetation nearby is evidence of many meals eaten here. The otter is working on the gull's head (which, if you decide, you can see by clicking on the image).

One of these otters is an experienced hunter who seems to take on large prey the others pass up.

On rainy morning the gang sees a Great Blue Heron resting on shore and they all submerge and disappear.

30 seconds later the water around the heron boils and an otter lunges at the heron who leaps to safety just in time.

This Pelican wasn't so lucky. It was one of many that the otters caught as they landed on the lagoon to rest during their meanderings down the coast. As the months went on, fewer and fewer Pelicans spent any time on the water and otters switched to other prey.